Hierarchical control for reference trajectory tracking of autonomous vehicles

A trajectory tracking controller is designed for autonomous vehicles based on a hierarchical architecture to make the lateral deviation of the autonomous vehicle with respect to a given reference trajectory converge to zero. The controller consists of two sub controllers: kinematic controller and dynamic controller. Based on the kinematics of tracking reference trajectory, a desired yaw rate is calculated by kinematic controller to make the lateral deviation global asymptotic stability. Then, steering wheel angle is calculated by a vehicle dynamic controller to make the vehicle yaw rate converge to the desired value. Meanwhile, conditional integration method is used in the sub controllers considering the uncertainty of parameters and constraints of actuators. This method can guarantee global asymptotic stability of tracking reference values. Then based on small-gain theorem, the condition of the finite-gain L stability is given. Finally the effectiveness and robustness of the controller are validated by real vehicle test.